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Pharmaceutical Sciences Faculty Patents
Pharmaceutical Sciences
7-16-1991
3-Hydroxy-N-Methylpyrrolidone and Use as
Transdermal Enhancer
George A. Digenis
University of Kentucky, [email protected]
Walter J. Doll
University of Kentucky
Amale Hawi
University of Kentucky
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Recommended Citation
Digenis, George A.; Doll, Walter J.; and Hawi, Amale, "3-Hydroxy-N-Methylpyrrolidone and Use as Transdermal Enhancer" (1991).
Pharmaceutical Sciences Faculty Patents. 136.
http://uknowledge.uky.edu/ps_patents/136
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United States Patent [191
[11]
[45]
Digenis et al.
[54] 3-HYDROXY-N-METHYLPYRROLIDONE
Patent Number:
Date of Patent:
[56]
5,032,402
Jul. 16, 1991
References Cited
AND USE AS TRANSDERMAL ENHANCER
U.S. PATENT DOCUMENTS
[75] Inventors: GeorgeA. Digenis; Walter J. Doll;
Amale Ham‘, all of Lexington, Ky.
4,039,664
8/1977
4,537,776
8/1985
Stoughton ......................... .. 424/180
Cooper ......... ..
4,568,343
2/1986
Leeper .............................. .. 604/896
Primary Examiner—Thurman Page
[73} Assignee:
The University of Kentucky Research
Assistant Examiner-D. Gabrielle Phelan
Foundation, Lexington, Ky.
Attorney, Agent, or Firm-Lowe, Price, LeBlanc &
Becker
[21] Appl. No.: 554,501
[22] Filed:
[5?]
ABSTRACT
The novel compound, 3-hydroxy-N-methylpyrroli
done, is effective as a transdermal enhancer for the
Jul. 19, 1990
absorption of drugs through the skin of humans and
animals. The 3-hydroxy-N-methylpyrrolidone is pre
pared from delta-butyrolactone which is converted to‘
methyl 2,4-dibromobutyrate, this intermediate is re
acted with methylamine to form N-methyl-2,4
Related US. Application Data
‘ [62]
Division of Ser. No. 263,384, Oct. 27, 1988, Pat. No.
4,973,708.
dibromobutyramide, this intermediate is converted to
3~bromo-N-methyl-2-pyrrolidone by ring closure, and
[51]
Int. ci.5 ............................................ .. A61F13/02
[52]
us. c1. .................................. .. 424/44s;424/449;
[58]
Field of Search .............. .. 424/449, 448; 514/946,
514/946; 514/947
the 3-bromo-N-methyl-2-pyrrolidone is reacted with an
alkaline earth metal carbonate or alkaline metal carbon
ate to form 3-hydroxy-N-methyl-Z-pyrrolidone.
514/947
3 Claims, 3 Drawing Sheets
a CONTROL
. NH?
I 3' HYDRUXY-NMP
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2"
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US. Patent
July 16, 1991
Sheet} of 3
5,032,402
A CONTROL
0 NHP
B 3"’ HYDROXY-NMP
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FIGURE 1
1'
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40
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50
US. Patent
- July 16, 1991 _
Sheet 2 of 3
5,032,402
El CONTROL
0 NMP
i S-HYDRDXY-NMP
40
Z
a
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n a n
a II
30—
i‘
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FIGURE 2
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US. Patent
July 16, 1991
FIGURE
Sheet 3 of 3
5,032,402
3
o
1530 45
TIME (MIN)
1
5,032,402
3-HYDROXY-N-METHYLPYRROLIDONE AND
USE AS TRANSDERMAL ENHANCER
have shown very little irritation or sensitizaticn poten
tial. Ames type assays and chronic exposure studies
have not revealed any significant toxicity, Wells et a1,
This is a division of application Ser. No. 07/263,384
?led Oct. 27, 1988, now US. Pat. No. 4,973,708, dated
Nov. 27, 1990.
Mutagenicity and Cytotoxicity of N-methyl-2-pyrroli
done and 4-(methyl amino) Butanoic Acid in the Sal
monella/microsome Assay. J. Appl. Tox., 8, 135-139
(1988). N-methylpyrrolidone has also been shown to be
an effective penetration enhancer. Barry et a1, Optimi
zation of Bioavailability of Topical Steroids: Penetra
tion Enhancers Under Occlusion. J. Inv. Derm., 82,
49-52 (1984); Akter et a1, Absorption Through Human
Skin of Ibuprofen and Flurbiprofen; Effect of Dose
TECHNICAL FIELD
This invention relates to a new composition for drug
delivery and more particularly relates to use of the
compound 3-hydroxy-N-methylpyrrolidone as a trans
dermal enhancer for the absorption of drugs into hu
mans and animals by absorption through the skin..
BACKGROUND ART
2
N-methyl-Z-pyrrolidone in the Rat. Drug Met. Disps,
16, 243-249 (1988). Animal and human experiments
15
Transdermal absorption is currently one of the fastest
growing methods of drug delivery. Transdermal thera
peutic systems are self-contained dosage forms that,
Variation, Deposited Drug Films, Occlusion and the
Penetration Enhancer N-methyl-Z-pyrrolidone. J.
Pharm. Pharmacol., 37, 27-37 (1984); Holegaard et a1,
Vehicle Effect on Topical Drug Delivery IV. Effect of
N-methylpyrrolidone and Polar Lipids on Percutane
when applied to intact skin, deliver drug(s) at a con 20 ous Transport. Int. J. Pharm., 43, 233-240 (1988);
trolled rate to the systemic circulation. Advantages of
Sugibayashi et al, Effect of Several Penetration En
using the transdermal route include: enhanced thera
hancers on the Percutaneous Absorption of Indometha
peutic efficacy, reduction in the frequency of dosing,
cin in Hairless Rat. Chem. Pharm. Bull, 36, 1519-1528
reduction of side effects due to optimization of the
(1988); Bennett et al, Optimization of Bioavailability of
25
blood-concentration versus time pro?le, increased pa
Topical Steroids: Non-Occluded penetration Enhancers
tient compliance due to elimination of multiple dosing
Under Thermodynamic Control. J. Pharm. Pharmacol,
37, 298-304 (1985); Sasaki et al, Enhancing Effect of
Pyrrolidone Derivatives on Transdermal Drug Deliv
ery. 1.1m. J. Pharm., 44, 15-24 (1988); Lee et al, Toxic
schedules, bypassing the hepatic “?rst-pass" metabo
lism, avoiding gastrointestinal incompatibilities and
providing a predictable and extended duration of activ
ity. However, the main function of the skin is to act as
a barrier to entering compounds. As a consequence,
transdermal therapy has so far been restricted to a lim
ity of N-methyl-Z-pyrrolidone (NMP): Tetratog‘enic,
Subchronic and Two-Year Inhalation Studies, Fund.
Appl. T0x., 9, 222-235 (1987).
'
There remains a need in the art of transdermal deliv
ited number of drugs that possess the desirable physio
chemical properties for diffusion across the skin barrier.
One effective method of overcoming the barrier func 35 ery for a penetration enhancer which is safe, effective,
and provides advantages not known to penetration en
tion of the skin is to include a penetration enhancer in
hancers of the prior art.
the formulation of a transdermal therapeutic system.
See Barry, Brian W.: Dermatological Formulations: Per
DISCLOSURE OF THE INVENTION
cutaneous Absorption (Dekker, New York, 1983);
Bronough et al, Percutaneous Absorption, Mechanisms
Methodology-Drug Delivery, (Marcel Dekker, New
40
It is accordingly one object of the present invention
to provide a novel penetration enhancer for use in trans
dermal drug delivery.
York, N. Y. 1985); and Monkhouse et al, Transdermal
A further object of the present invention is to provide
as a novel chemical compound, 3-hydroxy-N-methyl
pyrrolidone having advantageous characteristics as a
drug delivery-problems and promises. Drug Dev. Ind.
Pharm., 14, 183-209 (1988).
A penetration enhancer is a chemical compound that,
when included in a formulation, temporarily increases
the permeability of the skin to the drug allowing more
of the drug to be absorbed in a shorter period of time.
penetration enhancer in transdermal delivery systems.
A further object of the invention is to provide meth
ods for preparation of the novel penetration enhancer,
3-hydroxy-Nmethylpyrrolidone.
Several different types of penetration enhancers have
been reported such as dimethylsulfoxide, n-decyl 50 A still further object of the present invention is to
provide transdermal delivery systems which contain as
methyl sulfoxide, N,N-dimethylacetamide, N,N-dime
thylformamide,
1-dodecylazacycloheptan-Z-one a safe and effective penetration enhancer, 3-hydroxy-N
methylpyrrolidone.
(Azone), propylene glycol, ethanol, pyrrolidones such
Other objects and advantages of the present invention
as N-methyl-Z-pyrrolidone (NMP) and surfactants. See
Bronough et a1, supra, and Stoughton et a1, Azone: A 55 will become apparent as the description thereof pro
ceeds.
New Non-toxic enhancer of percutaneous penetration.
In satisfaction of the foregoing objects and advan
Drug Dev. Ind. Pharm., 9, 725-744 (1983).
tages, there is provided by this invention a novel pene
N-methyl-2-pyrrolidone is a versatile solvent which
tration enhancing compound, 3-hydroxy-N-methylpyr
is miscible with water, ethyl alcohol, ether, chloroform,
benzene, ethyl acetate and carbon disul?de. N-methyl
rolidone.
There is also provided _by this invention a method for
pyrrolidone has been widely used as a solvent in indus
trial processes such as petroleum re?ning, GAF Corp.:
“M-Pyrol (N-methyl-Z-pyrrolidone) Handbook”, GAF
Corp., New York, 1972. It is currently used as a solubi
lizing agent in topical and parenteral veterinary phar
maceuticals and is now under consideration for use in
products intended for humans, Wells, D.A. et al: Dispo
sition and Metabolism of Double-Labeled [3H and 14C]
65
preparation of 3-hydroxy-N-methylpyrrolidone which
comprises conversion of delta-butyrolactone to methyl
2,4-dibromobutyrate, conversion of the methyl-2,4
dibromobutyrate to N-methyl-2,4-dibromobutyramide,
ring closure of the N-methyl-2,4-dibromobutyramide to
form 3-bromo-N-methyl-2-pyrrolidone, and conversion
of the 3-bromo-N-methyl-2-pyrrolidone to 3-hydroxy
5,032,402
3
4
N-methyl-Z-pyrrolidone by reaction with alkali metal
aqueous solution at a temperature of below ambient in
carbonate.
order to form N-methyl-2,4-dibromobutyramide. Then
butyramide is then recovered and puri?ed to obtain the
The present invention also provides transdermal
compositions comprising as the penetration enhancer,
3-hydroxy-N-methyl-Z-pyrrolidone. The present inven
tion also provides a method for delivery of drugs
through the human skin which comprises preparation of
a transdermal drug delivery system containing 3
solid intermediate product.
The N-methyl-2,4-dibromobutyramide is then con
verted to 3-bromo-N-methyl-Z-pyrrolidone by reaction
with alkali metal alkoxide to effect ring closure. In this
reaction, an alcoholic solution of the N-methyl2,4->
hydroxy-N-methylpyrrolidone as a penetration en
hancer, and applying the transdermal composition to
the human skin.
0
added drop-wise to the mixture under an inert atmo
sphere. After the reaction is complete, the mixture is
BRIEF DESCRIPTION OF DRAWINGS
?ltered and the alcohol removed under reduced pres
sure. This solid intermediate is then purified to provide
Reference is now made to the accompanying draw
ings wherein:
15
FIG. 1 is a graph showing a comparison of the per
cent penetration of 131I-labeled Clioquinol when deliv
The ‘recovered 3-bromo-N-methyl-Z-pyrrolidone is
ered with 3-hydroxy-N-methylpyrrolidone, N-methyl
or alkaline earth metal carbonate in a substantially stoi
chiometric reaction and in an aqueous medium, Prefera
bly the reactant is added to a solution of the 3-bromo-N
125I-labelecl Clioquinol using 3-hydroxy-N-methylpyr
rolidone, N-methylpyrrolidone, and without an en
methyl-Z-pyrrolidone under agitation and while heating
hancer; and
in the range of 75°—l25° C. After the reaction is com
FIG. 3 is an HPLC radiochromatogram of the 5
the
a yellow liquid intermediate product.
then converted to the 3-hydroxy-N-methyl-2-pyrroli
done of this invention by reaction with an alkali metal
pyrrolidone, and without an enhancer;
FIG. 2 is a graph showing the percent penetration of
chloro-8-hydroxy-7-[l31I]-iodoquinoline,
dibromobutyramide is formed and freshly prepared
alkali metal alkoxide, preferably sodium ethoxide, is
plete, the 3-hydroxy-N-methylpyrrolidine white solid
product is recovered and purified.
drug
chosen to test the penetration enhancing characteristics
of the compound of the invention.
The following is a schematic showing this four-step
reaction.
BEST MODE FOR CARRYING OUT THE
INVENTION
30
It has been discovered according to this invention
that 3-hydroxy-N-methylpyrrolidone, also known as
3-hydroxy-N~methyl-2-pyrrolidone, is an effective pen
etration enhancer when used in transdermal drug deliv
ery systems. 3-hydroxy-N-methylpyrrolidone is a novel
compound prepared according to methods described
herein. In general, the compound is a white solid having
a melting point of 7l°-72° C. and is of the following
Br
(1) En
O
l
COgCHj,
(2) CH3OH E
Br
2
structural formula:
CH3
45
3
4
OH
This novel compound is prepared through a series of
novel chemical steps, preferably using as the basic start
ing material delta-butyrolactone. In a preferred proce
dure, delta-butyrolactone is reacted with bromine in the
presence of a bromide compound such as phosphorus
tribromide and under an elevated temperature in the
range of 75°—l25° C. In a preferred procedure, the bro
0
l
CH3
5
As pointed out above, a penetration enhancer is a
mide compound and delta-butyrolactone are mixed 55
chemical
compound which, when included in a trans
with agitation and at an elevated temperature, liquid
dermal formulation, affects the skin of a human by in
bromine is slowly added. The temperature may be con
creasing permeability of the skin to allow more of a
trolled in the preferred range by the rate of addition of
drug to be absorbed in a shorter period of time. The
the bromine and by external heating. Preferably the
penetration enhancer is normally contained in a formu
amount of bromine added to the butyrolactone is in the
lation, called a transdermal composition, in combination
molecular ratio of about 1:2. Bromine addition is
with the appropriate drug to be delivered and other
stopped when HBr evolution becomes evident, after
known components of the formulation. According to
which the reaction mixture is cooled and combined
this invention, it has been discovered that the 3- hy
with methanol. The resulting solution is then saturated
droxy-N-methylpyrrolidone provides unexpectedly
with HCl gas, the methanol is removed and methyl-2,4
improved effects as a penetration enhancer when incor
dibromobutyrate is removed as a pale yellow liquid.
porated into a transdermal formulation. As mentioned
In a second step of the reaction, the methyl-2,4
dibromobutyrate is reacted with methylamine in an
herein, N-methylpyrrolidone is a known penetration
5
5,032,402
6
enhancer. In studies leading to this invention using the
prior art compound, N-methyl-Z-pyrrolidone, it was
discovered that a major metabolite of N-methylpyrroli
done which is excreted in the urine is 3-hydroxy-N
The above and other drugs can be present in the
reservoir alone or in combination form with pharma
methy1-2-pyrro1idone. The subsequent synthesis of this
compound, and closer examination of physical proper
ties of the compound, led to the present discovery that
3-hydroxy-N-methylpyrrolidone possesses several ad
carriers that do not adversely affect the drug, the host,
or the material comprising the drug delivery device.
Suitable pharmaceutical carriers include sterile water;
ceutical carriers. The pharmaceutical carriers accept
able for the purpose of this invention are the art known
saline, dextrose; dextrose in water or saline; condensa
tion products of castor oil and ethylene oxide combin
0 ing about 30 to about 35 moles of ethylene oxide per
mole of castor oil; liquid glyceryl triester of a lower
methylpyrrolidone provides at least equal and often
superior enhancement of transdermal absorption while
molecular weight fatty acid; lower alkanols; oils such as
exposing the body to a lower metabolic burden. Fur
corn oil; peanut oil, sesame oil and the like, with emulsi
ther, 3-hydroxy-N-methy1pyrrolidone is a “softer”
?ers such as mono-or di-glyceride of a fatty acid, or a
vantages over similar compounds such as N-methylpyr
rolidone as a penetration enhancer. Thus, 3-hydroxy-N
xenobiotic to the body because no energy will be ex
phosphatide, e.g., lecithin, and the like; glycols; polyal
pended in metabolic processes after the compound’s
absorption into the systemic circulation. Also, in view
of the apparent safety of N-methylpyrrolidone, its
kylene glycols; aqueous media in the presence of a sus
major metabolite, 3-hydroxy-N-methylpyrrolidone,
like, alone, or with suitable dispensing agents such as
lecithin; polyoxyethylene stearate; and the like. The _
carrier may also contain adjuvants such as preserving,
pending agent, for example, sodium carboxymethylcel
lulose; sodium alginate; poly(vinylpyrolidone); and the
would be expected to have an even lower toxicity.
The 3-hydroxy-N-methylpyrrolidone of this inven
tion may be used as the penetration enhancer in any
stabilizing, wetting, emulsifying agents and the like
transdermal drug delivery system in which it is effec
together with the penetration enhancer of this inven
tive. It is considered that the 3-hydroxy-N-methylpyr
tion.
r'olidone is compatible with all known drugs which are 25
The following examples are presented to illustrate the
systematically-active and can be delivered in a trans
invention. However, it is not to be considered as limited
dermal system to be absorbed by the body surface. As is
known, a transdermal delivery system comprises or
reservoir for the composition to be transferred includ
thereto. In the examples and through the speci?cation,
parts are by weight unless otherwise indicated.
ing the drug of choice, the carrier, and the penetration
EXAMPLE 1
enhancer. In general, the reservoir will be contained
Synthesis of 3-hydr0xy-N-methy1-2-Pyrrolidone
between a backing member and a pressure-sensitive
adhesive which enables the transdermal device to be
applied to the skin. Transdermal delivery systems are
.
General. Melting points were determined on a Fish
er-Johns melting point apparatus and are uncorrected.
H-NMR
and C-NMR spectra were obtained using a
well known in the art and described, for example, in U. 35
Varian
Gemini
200MHz or Varian XL-300 300 MHZ
S. Pat. Nos. 3,598,122, 3,797,494, and 4,230,105. It is
spectrometer. Mass spectra were run on a Kratos M550
considered according to the present invention that the
TA mass spectrometer with. a KratosDS90 data system.
Infrared (IR) spectra were recorded on a Perkin-Elmer
penetration enhancer of this invention can be used in all
such systems.
Ratio Recording spectrophotometer. Microanalysis
In practicing this invention one can employ any sys
were performed by Atlantic Microlab, Inc., Atlanta,
temically active drug which will be absorbed by the
body surface to which the transdermal bandage is ap
plied, consistent with their known dosages and uses. Of
Ga.
'
Reactions were routinely followed by thin layer
course, the amount of drug necessary to obtain the
chromatography (TLC) using Whatman K6F silica gel
chloride, and thiopropazate hydrochloride; Hormones;
(Aldrich, Cat. No. 25,653-6, lot 1413BM), methanol
(Fisher, Cat. No. A-412, lot 854027), Methylamine, 40
desired therapeutic effect will vary depending on the 45 plates. Spots were visualized by exposure to iodine
vapor or uv lamp (254 nm). Column chromatography
particular drug used. Suitable systemic drugs include,
was carried out using silica gel (Davidson Chemical,
without limitation, Anti-microbial agents such as peni
Baltimore, Md.).
cillin and tetracycline; Sedatives and Hypnotics such as
Materials. Delta-Butyrolactone (Aldrich, Cat. No.
pentabarbital sodium and phenobarbital; Psychic Ener
B10,360-8, lot 2710BK, 99%), Bromine (J. T. Baker,
gizers such as 3-(2-aminopropyl) indole acetate; tran
Cat. No. 1-9760, lot 849381), Phosphorous tribromide
quilizers such as reserpine, chloropromazine hydro
Antipyretics such as aspirin, salicylamide, and sodium
salicylate; morphine and other narcotic analgesics; An
tidiabetics, e.g., insulin; Cardiovascular Agents, e.g.,
wt % solution in water (Aldrich, Cat. No. M2,775-1, lot
55
nitroglycerin, and cardiac glycosides such as digitoxin,
Anti-spasmodics such as atropine, and methscololamine
bromide; Anti-malarials such as the 4-aminoquinolines;
and Nutritional Agents such as vitamins, essential amino
acids, and essential fats.
03804CT), absolute ethanol (Midwest Solvents Com
pany of I11.), potassium carbonate (Aldrich, Cat. No.
20,961-9, lot O4006BP, 99+%).
A. Methyl 2,4'dibromobutyrate. Phosphorous tribroi
mide (2.0 ml, 5.7 gm, 0.021 mole) was added to ‘del
tabutyrolactone (100.8 gm, 1.17 mole) and the mixture
known dosages and uses can be administered. Suitable
was heated to 100° C. while stirring. Bromine (30 m1,
93.4 grn, 0.59 mole) was slowly added dropwise beneath
drugs include without limitation: Antiperspirants, e.g.,
aluminum chloride; Deodorants, e.g., hexachlorophene,
the surface of the liquid. The temperature was con
trolled at ll0°-ll5° C. by the rate of addition of bro
Further, topically active drugs consistent with their
Astringents, e.g., tannic acid; Irritants, e.g., methyl
Agents; Anti-in?ammatory Agents; Anti-neoplastic
mine and an oil bath. Additional PBT} (1.0 ml, 2.85 gm,
0.011 mole) was added to the reaction vessel and bro
mine addition was then continued until HBr evolution
Agents, And Antibacterial Agents.
was evident (approx. 25 ml, 80 gm, 0.49 mole). The
salicylate, Keratolytics, e.g., benzoic acid; Antifungal
65
7
5,032,402
8
95% ethanol. After removal of the solvent, the product
reaction mixture was stirred and cooled to room tem
perature and ?nally cooled in an ice bath. The mixture
was puri?ed by column chromatography (silica gel,
was combined with methanol (480 ml) and the resulting
gradient elution using from chloroform to chloroform
/ethylacetate/methanol) to yield a white solid, (0.754
gm, 58.5%); m.p. 71°—72° C. IR(nujol) 3120(broad),
solution was saturated with HCl gas. The solution was
allowed to stand overnight at room temperature after
which the methanol was removed under reduced pres
sure. The residue was dissolved in ether, washed with
' 1670, 1400, 1305,‘ 1270 and 1170 cm31 1; H-NMR
(CDCl3) 8 1.98 (m, 1H, -CH2-CHOH-), 2.41 (m, 1H,
-CH2-CHOH-), 2.84 (s, 3H, ~N-CH3), 3.30 (m, 2H,
-CH2-N-), 4.30 (triplet of doublets, 1H, -CH-OH), 5.18
5% sodium bicarbonate solution, dried over magnesium
sulfate and ?ltered. The solvent was removed and the
residue distilled under reduced pressure to yield a clear
(d, 1H, -CH-OH), C-NMR, decoupled (CDC13) 27.38,
pale yellow liquid, 2 (216.4 gm, 71%); hp. 80°-85° C. @
-CH2-CHOH-), 29.74 (-N-CH3), 45.74 (-CH2-N-), 69.41
(-CH-OH-), 175.53 -CHOH-CO-N-) ppm. Partially de
coupled and Z-dimensional HETCOR spectra support
the assignments as given. Anal. calcd. for C5H9NO2
2-3 mm ofHg, IR(neat) 1775, 1735, 1470 and l380—l130
cm-l; H-NMR (CDC13) 5 2.54 (q, 2H, -CH2-CHBr-),
3.55 (t, 2H, Br-CH1-CH2-), 3.81 (s, 3H, O-CH3), 4.56 (t,
1H, -CH2-CHBr-); C-NMR, decoupled (CDC13) 29.60,
15
36.69, 43.24, 53.10, 169.77 ppm. Anal. calcd. for
C5H3O2Br2 (295.934): C, 23.10; H, 3.10. Found: C,
23.39; H, 3.14%.
B. N-Methyl-2,4-dibromobutyramide. Methyl 2,4
(115.129): C, 52.16; H, 7.88; N, 12.17%. Ms(70eV) Extract molecular ion M+ calculated for 115.06332,
Found: 115.0634. Fragmentation pattern: 86 (M-29); 54
(M-58); 42 (M-73).
EXAMPLE 2
dibromobutyrate (50 gm, 0.192 mole) was mixed with 20
40 wt % methylamine in aqueous solution (20.0 ml, 7.22
Radioiodination of 5-chloro-8-hydroxy-iodoquinoline.
gm, 0.232 mole) with stirring and cooling in an ice bath.
The reaction mixture was stirred for 16 hours at 5° C.,
This example prepares the radioiodinated control,
chromatography (silica gel, gradient elution hexane/
chloroform to chloroform/ethylacetate) to yield an
Materials. Sodium Iodide-125 (New England Nuclear
NEZ 033, radiochemical and radionuclidic purity
compound was used in the next step without further
035H, radiochemical and radionuclidic purity 99%),
puri?cation. A small portion was further puri?ed for
elemental analysis; m.p. 48°—49° C. IR(KBr) 3450, 1660,
1570, 1415, 1240 and 1210 cm-1; H-NMR (CDC13)
lot 3128LJ Cat No. 25,044-9), 5-chloro-8-hydroxy
7iodoquinoline (Aldrich, lot 0513KL Cat. No.
5-chloro-8-hydroxy-iodoquinoline to be used in tests
chloroform (100 ml) was then added and the organic
layer washed with water. The organic extract was dried 25 described hereinafter to determine the effect of penetra
tion of the 3-hydroxy-N-methylpyrrolidone of this in
over magnesium sulfate, ?ltered and the solvent re
vention.
moved. The crude product was puri?ed by column
off-white solid, (25.4 gm, 51.7%): m.p. 42°-47° C. The 30 99%), Sodium iodide-131 (New England Nuclear NEZ ;
62.48 (m, 1H, -CH2-CHBr-), 2.79(m, 1H, -CH2-CHBy-),
(d, 3H, -NH2-CH3-), 3.55 (t, 2H, Br-CHZ-Cl-h), 4.54
(dd, lH,"CHBr-); 6.39 (s, broad, 1H, -NH-CH3), C
NMR, decoupled (CDC13) 26.83, 30.27, 37.60, 48.26,
5-chloro-8-hydroxy quinoline hydrochloride (Aldrich,
35
line. An aqueous solution (0.1N NaOH) containing ap
proximately one mCi of Nal25I was diluted to 0.5 ml
with methanol. Three iodobeads were added and the
solution was left to stand for 5 minutes at room tempera
168.65 ppm. Anal. calcd. for C5H9NBr2O (258.949): C,
23.19; H, 3.50; N, 5.41. Foundrc, 23.53; H, 3.44; N,
5.29%.
C. 3-Bromo-N-methyl-2-pyrr0lidone. To a stirred
solution of N-methyl-2,4-dibromobutyramide (25.9 gm,
0.1 mole) in 65 ml of dry ethanol, kept under nitrogen,
was added dropwise an equimolar quantity of freshly
22,406-5), Iodobeads (Pierce Chemical Company No.
28666).
Synthesis of 5-chloro-8-hydroxy-7[l25I]-lodoquino
ture. 5-Chloro-8-hydroxyquinoline (0.5 ml of a stock
solution containing 200 ug/ml in methanol) was added
and the reaction vessel was shaken occasionally for 30
45 minutes. The iodobeads were then removed, 5-chloro-8
hydroxy-7-iodoquinoline (5.0 ml of a stock solution
containing 1 mg/ml in methanol) was added followed
by 20.0 ml of puri?ed water. The resulting white precip
prepared sodium ethoxide (2.3 gm Na in 50 ml ethanol)
over 40 minutes. After two hours the mixture was ?l
tered and the ethanol removed under reduced pressure.
The residue was dissolved in chloroform and washed
itate was ?ltered and washed with water until the ?l
with water, then washed with saturated aqueous NaCl. 50 trate activity was at background levels. The product
was then dissolved in CHZCLZ (10 ml), transferred to a
Removal of the solvent and distillation under reduced
25 ml pearshaped ?ask and the solvent removed under ‘
reduced pressure. Assay by uv spectroscopy at 256 nm
pressure yielded a yellow liquid, (11.55 gm, 65.2%); b.p.
90°-94° C. @ 0.1-1 mm. IR(neat) 1700, 1495,1440, 1405
and 1300 cm-1; H-NMR (CDCl3) 8 2.32 (m, 1H, -CH2
CHBr-), 2.72 (sextet, 1H, -CH2-CHBr-), 2.90 (s, 3H,
-N-CH3), 3.32 (m, 1H, N-cH2-CH3-), 3.58 (m, 1H, N
CH2-CH2-), 4.42 (dd, 1H, -CH2-CHBr-); C-NMR, de
coupled (CDC13) 33.6, 35.1, 44.2, 47.5, 171.5 ppm. Anal.
calcd. for C5H3B1'NO (178.03): C, 33.73; H, 4.53; N,
7.87. Found: C, 33.81; H, 4.52; N, 7.82%.
D. 3-Hydroxy-N-methyl-2-pyrrolidone -3-Bromo-N
methyl-Z-pyrrolidone (2.0 gm, 0.011 mole) was dis
solved in 100 ml of puri?ed water. Potassium carbonate
(2.33 gm, 0.017 mole) was added while stirring and the
55
showed that 4.84 mg of 5-chloro-8-hydroxy-7
iodoquinoline were recovered. Speci?c activity approx
imately lZOuCi/mg.
Synthesis of 5-chloro-8-hydroxy-7-[13lIl-lodoquino
line. This compound was prepared by the same proce
dure described above using Naml.
Assessment of Radiochemical .Purity; Analysis and
identi?cation of radiolabeled 5-chloro-8-hydroxy-7
iodoquinoline and determination of radiochemical pu
rity was performed by HPLC. The HPLC system used
consisted of the following components: isocratic pump
mixture was heated to l0O°-110° C. After 4 hours, the 65 (Altex model 110A, Berkley, Calif), ?xed volume injec
reaction mixture was poured onto ice and neutralized
tor (Rheodyne model 7125, Cotari, Calif), Waters u
with 1% aqueous HCl. Water was removed under re
Bondapak TM 018 reverse phase column (Waters Ass.,
duced pressure and the residue extracted with boiling
Milford, Mass.),_uv detector (Waters model 440, Mil
9
5,032,402
-
10
tector (Radiomatic Instruments and Chemicals, Tampa,
Fla.), dual channel strip chart recorder (Linear Instru
chamber was ?lled with normal saline containing 2%
albumin and 0.05% neomycin sulfate. Each cell was
maintained at 37° C. and stirred at 600 rpm. After the
cells had been allowed to equilibrate for 4 to 6 hours,
200 ul of a saturated ethanolic solution of 5-chloro-8
ments Inc., model 858, Irvine, Calif).
hydroxy-7-[l25I]-iodoquinoline (approx. 470 uCi, 0.44
ford, Mass), Radiomatic Model ES stream splitter
(Radiomatic Instruments and Chemicals, Tampa, Fla.),
Radiomatic Model HP ?ow-through radioactivity de
_
Samples were introduced using a 50ul ?xed volume
mg) was applied to the donor side of each cell. This was
injection loop. A mobile phase containing 70% metha
nol (Fisher HPLC grade, lot 874675) and 30% 0.05M
immediately followed by either 200 pl of absolute etha
nol for the control cells, 200 pl of 50% (w/v 3-hydroxy
phosphoric acid (Eastman, lot 620) was ?ltered using a
N-methylpyrrolidone in ethanol or an equimolar etha
0.22u ?lter, degassed under vacuum and delivered at a
nolic solution of N-methylpyrrolidone (43.1% w/v).
flow rate of 1.0 ml/min. After passing through the col
umn, the mobile phase effluent passed through the uv
The cells were then capped with ground glass stoppers.
At various time intervals, over an 80—100 hour period,
the entire contents of the receptor chamber was re
moved with a 10cc syringe and placed into a vial. The
receptor chamber was then re?lled with fresh solution.
After the last collection these vials were placed in a
well-type gamma counter and counted for I-l25 activ
detector set at 254 nm and was split by the stream split- '
ter. A percentage of the effluent was sent to the flow
through radioactivity detector and the remainder di
verted to waste. This detector mixed scintillation coc
tail (Scintiverse LC, Fisher) with the effluent in a ratio
of 4:1 (v/v). The uv output was recorded on one chan
nel of the strip chart recorder and the radioactivity _
output was recorded simultaneously on the second
ity.
At the time of dosing 200 pl of the saturated 5-chloro
8-hydroxy-7-[l25I]-iodoquinoline solution was placed
channel.
into separate vials to calculate the amount of activity
Standards were prepared by dissolving 5.0 mg of
(dose) applied to the skin.
unlabeled 5—chloro-8-hydroxy-7-iodoquinoline or 5.0
mg of S-chloro-8-hydroxyquinoline in 100 ml of mobile 25
EXAMPLE 4
phase to make a ?nal concentration of 50 ug/ml. Radio
In this example, 3-hydroxy-N-methyl pyrrolidone
active samples were prepared by dissolving the reaction
product (4.84 mg) in methanol, taking a small aliquot
was tested for its use as a percutaneous penetration
(100 ul), evaporating and reconstituting in mobile phase.
enhancer. In vitro studies were carried out using Franz
The retention time for 5-chloro-8-hydroxy-7
iodoquinoline was 10.5 minutes. 5-chloro-8-hydrox
yquinoline eluted with the solvent front at 3 minutes.
An HPLC chromatogram for 5-chloro-8-hydroxy-7
[131I]-i0doquinoline is shown in FIG. 3. In FIG. 3, the
upper tracing represents UV detection of radioiodina
type diffusion cells. The penetration enhancing proper
ties of 3-hydroxy-N-methylpyrrolidone was compared
hance the penetration of drugs through the skin.
tion product at 254 nm; A: solvent front/ 5-chloro-8
This drug, known as Clioquinol USP, is currently mar
hydroxyquinoline, B: 5-chloro-8-hydroxy-7-iodoquino
keted by Ciba (Ciba Pharmaceutical Company, 556
line. Lower tracing represents radioactivity detection
Morris Avenue, Summit, N. J. 07901), as a topical an
to N-methyl pyrrolidone, a compound known to en
For these in vitro studies radioiodinated 5-chloro-8
hydroxy-7-iodoquinoline was chosen as a model drug.
which was monitored continuously using a flow
tibacterial/antifungal agent tradenamed Vioform TM . It
through liquid scintillation counter. Only one radioac
tive peak (lower tracing) was detected that corresponds
to the uv peak of 5-chloro-8-hydroxy-7-iodoquinoline.
was chosen because 1) it is a drug that is absorbed very
EXAMPLE‘ 3
a radiolabeled analogue. This radiolabeled marker is
In vitro penetration of radioiodinated
S-chloro-8-hydroxy-7-iodoquinoline.
General. Standard Franz diffusion cells (15 mm id,
O-ring design) were manufactured by Crown Glass
slowly through the skin and 2) Clioquinol inherently
has iodine in its structure, allowing easy preparation of
conveniently used to follow the penetration of the drug
45 through the skin.
Franz diffusion cells are designed to mimic in vivo
conditions. A ?nite dose of drug is applied to the stra
' tum corneum side of the skin and penetration is fol
lowed by analyzing for the drug in the receptor phase
Inc., Somerville, N. J. The cell caps were modi?ed with
underneath. In these studies the amount of drug cross
ground glass joints to ?t 14/20 ground glass stoppers. A
ing the skin barrier is estimated by counting total radio
activity in the receptor phase. While no excised tissue
has been found to duplicate in vivo absorption in hu
mans, excised human skin is generally regarded as the
Franz diffusion cell drive consol F-DCD-9 was also
manufactured by Crown Glass. A Vandercamp 2500
recirculating water bath was used to maintain the cells
at 37° C. Split thickness human allograph tissues (0.015
in. thickness), thigh back area, was ‘obtained from the
Tissue Transplant Bank, St. Agnes Medical Center,
55 best substitute and was therefore used in these studies.
In a preliminary study, the transdermal absorption of
Clioquinol was evaluated in the presence of 3-hydroxy
Philadelphia, Pa. Samples were counted in a Packard
Auto-Gamma Scintillation Spectrometerv
Materials. Sterile Saline (0.9% Sodium Chloride
USP, Travenol, NDC 0338-0049-04 lot 0056747), Albu
min (Bovine, fraction v, Sigma A-4503 lot l27F-0877),
N-Methyl-Z-pyrrolidone (Aldrich 99+% Cat No.
24,279-9 lot 04402TP), Neomycin Sulfate (Sigma N
1876 lot 66F-0l51), absolute ethanol (Midwest Solvents
Company of 111.).
Procedure. Human allograph tissue, which had been
stored at —-70° C., was thawed and immediately
mounted in a Franz type diffusion cell. The receptor
N-methylpyrrolidone, N-methylpyrrolidone, and in the
60
absence of enhancer. An ethanolic solution of [I-l3l]
Clioquinol was applied to 3 cells followed by either
ethanol (control), 50% 3-hydroxy-N~methyl-pyrroli
done in ethanol or an equimolar solution of N-methyl
pyrrolidone. In FIG. 1, the percent penetration of 5
chloro-8-hydroxy-7-[131I]-iodoquinoline
through
65 human skin is illustrated. The amount of 5-chloro-8
hydroxy-7-[l3lI]-iodoquinoline activity applied is equal
to 100%. As shown in FIG. 1, the extent of enhance
ment by 3-hydroxy-N-methyl-pyrrolidone is clearly
11
5,032,402
12
mechanism being more dominant than others for a par
evident. At 48.5 hours the amount of I-l31 Clioquinol
that had penetrated through the skin in the presence of
ticular type of enhancer. Although the mechanism is
not known, since 3-hydroxy-N-methylpyrrolidone ef
fectively enhances the absorption of a poorly absorbed
3-hydroxy-N-methyl-pyrrolidone (10.2% absorbed)
was 3.9 times greater than the control (2.6% absorbed)
compound like Clioquinol, this suggests that 3-hydroxy
N-methylpyrrolidone will be effective for enhancing
and 1.5 times more than with N-methylpyrrolidone
(6.5% absorbed).
The study was repeated using I-l25 labeled Cli
oquinol. Iodine-125 was used because the longer half
the percutaneous absorption of many other poorly ab
sorbed compounds.
In conclusion, a novel compound, 3-hydroxy-N
life (ti =60d) and lower energy gamma ray (0.035 Mev)
were better suited to our experimental design. The re
. sults are shown in FIG. 2. In FIG. 2, the percent pene
methylpyrrolidone, was synthesized and was shown to
effectively enhance the in-vitro absorption of a model
‘tration of 5-chloro-8-hydroxy-7-[125I]-iodoquinoline
drug. Further, 3-hydroxy-N-methylpyrrolidone is
through the human skin is illustrated. The amount of
shown to be more effective than N-methylpyrrolidone
5-chloro-8-hydroxy-7P25I]-iodoquinoline applied is
in enhancing the absorption of drugs. Because it is a
equal to 100%. The relative order of enhancement was
found to be the same with 3-hydroxy~N-methylpyr
metabolite, 3-hydroxy-N-methylpyrrolidone should be
metabolically softer to the body and less irritating than
other compounds such as N-methylpyrrolidone. The
introduction of a potent, non-toxic and non-irritating
compound that can effectively enhance the penetration
of poorly absorbed drugs would open the way for the
clinical use of transdermal therapeutic systems contain
ing drugs that otherwise could not be administered by
rolone>N-methylpyrrolone>control. The amount of
Clioquinol penetrating the skin in the presence of 3
hydroxy-N-methylpyrrolidone (40.0% absorbed) was
1.8 times higher than the control (19.5% absorbed) and
1.3 times greater than with N-methyl-pyrrolidone
(27.8% absorbed ) at 85.5 hours. Alternatively, the same
amount of Clioquinol was absorbed in approximately 32
hours in the presence of 3-hydroxy-N-methylpyrroli
this route.
done (19% absorbed) as was absorbed in 85 hours in the 25
absence of 3-hydroxy-N-methylpyrrolidone.
The results of these experiments indicate that 3
hydroxy-N-methylpyrrolidone shows great potential
for use as a percutaneous penetration enhancer. The
absorption of Clioquinol was clearly increased in the 30
presence of 3-hydroxy-N-methylpyrrolidone as com
The invention has been described herein with refer
ence to certain preferred embodiments. However, as
obvious variations thereon will become apparent to
those skilled in the art, the invention is not to be consid
ered as limited thereto.
We claim:
I
1. An article of manufacture for the continuous ad
ministration of drugs by absorption through the skin
pared to its absorption in the presence of ethanol and
N-methylpyrrolidone. In addition, since 3-hydroxy-N
which comprises as a penetration enhancer for the drug,
methylpyrrolidone is a major metabolite of N-methyl
pyrrolidone, it should offer the advantage of being a
lower toxicological burden to the body.
The mechanism by which penetration enhancers
wherein the article of manufacture comprises a reser
altering the partitioning behavior of the drug between
the human skin which comprises preparation of a drug
the stratum corneum and the underlying dermal tissues
delivery system which contains the drug and as a pene
and solubilizing the lipid components of the stratum
corneum. Most likely penetration enhancers work by a
tration enhancer, 3-hydroxy-N-rnethylpyrrolidone, and
applying the composition to the human skin.
3-hydroxy-N-methylpyrrolidone.
2. An article of manufacture according to claim 1
voir for the drug and the penetration enhancer, a back
ing member, and a pressure-sensitive adhesive for appli
exert their effects has not been clearly established. Pos
cation of the article to the skin.
sible modes of action that have been suggested include
3. A method for the administration of drugs through
altering membrane fluidity in the stratum corneum, 40
combination of these and other mechanisms with one 45
55
65
it
i
it
i
III